Course CodeBHT256
Fee CodeS2
Duration (approx)100 hours
QualificationStatement of Attainment

There are lots of different reasons for creating a vertical garden or roof garden, and the way you develop the garden may be affected by the reason you create it. Common reasons might be:

  • Lack of space for a more extensive garden
  • To improve aesthetics of an ugly place (wall or roof)
  • Improving physical environment (eg. Reduce glare, modify temperature, filter air pollutants, reduce water run off and mitigate flood problems)
  • Urban farming –growing crops in an urban area

This is an excellent course for landscapers, interior plant scapers, environmental managers, architects, engineers, horticulturists or anyone else interested in learning about this fascinating subject.

Lesson Structure

  1. Scope & Nature of Roof and Vertical Gardens
  2. Construction Functional and Appropriate Vertical and Roof Gardens
  3. Climbing Plants and Structures for climbing
  4. Plants Suited to Roof and Vertical Gardens
  5. Adaptations for Other Plants in Roof and Vertical Gardens
  6. Container Growing
  7. Maintenance –watering, pest control
  8. Applications/Landscaping –Roof Gardens
  9. Applications/Landscaping –Vertical gardens


  • Discuss the nature and scope of vertical gardens and roof gardens in horticulture today.
  • Explain engineering considerations involved with the building of vertical and roof gardens, both on small and large scale projects.
  • Select appropriate materials and plan the way in which the non living components of the garden is created, in order to achieve an appropriate and sustainable
    • installation.
  • Select appropriate climbing plants for creating vertical or roof gardens, and determine appropriate strategies to cultivate those plants, in a variety if different situations.
  • Select appropriate plants for use in vertical or roof gardens, which are tolerant of the adverse growing conditions, having natural adaptations to growing under conditions that are encountered in these gardens.
  • Select and plan the cultivation of plants that lack natural adaptations to growing on roofs or vertical gardens; but which are none the less required to grow in these adverse conditions;
  • Explain a range of container growing techniques, in a range of different roof and vertical gardens, that may be used with a selection of different types of plants.
  • Identify and evaluate problems with vertical and roof gardens, and compare options for solving those problems
  • Plan the development of roof gardens for both small and large scale applications.
  • Plan the development of vertical gardens for both small and large scale applications.

Is the Building Suitable?

For a building that was not originally designed to support a green roof or wall:

  • You need to calculate the load (force or weight) at different points (where a garden attaches to or places a load on a building), and determine what structural requirements are needed at those points.
  • Upgrading the structure to deal with those increased loads must then be calculated.
  • Creative strategies might be considered to reduce the load to be created (e.g. lightweight potting materials, shallower potting media with automated irrigation, lightweight containers (e.g. fibreglass rather than concrete or ceramic), etc.
  • Creating a garden that can be supported by an old building, will often be excessive, and cause a project with older architecture to be abandoned.
  • Many green wall solutions involve the use of frameworks which are not attached to the building itself. Rather these are steel frames which are free-standing and sit close to the wall so they look as though they are attached, or at least the plants appear to be growing up the face of the wall. These frameworks are supported by the ground rather than the building but if used on balconies then loads may have to be calculated
  • Other problems might include the location of air-conditioning vents and exhaust pipes. Heat and fumes emitted might scorch plants in the immediate vicinity and cause physiological disorders. In the case of a green wall it may be possible to use plastic plants around such openings so as not to destroy the effect of continuity. On roofs, it may be possible to box around such areas using decorative trellis or something similar.
  • Buildings also offer an opportunity to harvest resources such as rainwater and solar radiation to generate power. For buildings which cannot takes heavy loads on the roof, it may be feasible to collect water in tanks at ground level, or below ground level, and pump it up for use in green walls and roof gardens. Solar panels may be used to harness power used for pumps and irrigation systems. It is likely that future city apartment blocks will be built to make the most of these resources for greener cityscapes.

The plants you choose to use will depend upon climatic, structural and aesthetic considerations for the roof or wall.

In cool, wet and humid environments, plants are less likely to suffer water stress but in dark, dry, hot and windy conditions it can be extremely difficult to keep any but the hardiest plants from suffering. Whilst this applies to plants growing outdoors, those growing indoors also suffer if grown in less than perfect environmental conditions.  For instance, those growing inside under air conditioning, next to heaters, in drafty locations, or in dusty environments, in homes and offices, foyers, lobbies, shopping complexes and restaurants may all suffer.

Green walls or roofs can be subject to microclimate variations caused by:

  • Shadowing – from surrounding buildings or trees.
  • Reflection/radiation – metal, glass, and masonry can all reflect or radiate heat causing hot or cool spots
  • Exposure – tall buildings can reduce or change wind patterns; those growing high up may be under more wind stress. Less ventilation can change air quality.
 Large roof or wall gardens with a large biomass will require more growing media for the roots, will have more weight in the live plant tissue, and need a much stronger structure to support the inevitable increased weight. Creating a garden on the roof of a hotel, with shade trees, and much more, will no doubt be more expensive, and more complex than installing a cover of low growing succulents across the roof of a gazebo.

 Some plants like many of the succulents and bromeliads look good with little attention; while others such as ferns may not as their vigorous growth means more production of older leaves dying back (which are unsightly and untidy),  as the new ones develop.

If a plant dies and needs to be replaced in the middle of a small roof or wall garden; you may be able to effect the change with a step ladder; but for a large installation, it may be necessary to use a travel tower or crane to replace the dead or ugly plant. This set up of equipment may also be needed periodically the change the display plants depending on the effects created with the display plants.



Green walls and roofs have become an extremely important part of urban horticulture over recent decades. 

Bringing significant quantities of vegetation into cities not only improves the aesthetic, but also improves air quality. Plants filter pollutants and produce oxygen. We know from international studies that most people are breathing poorer quality air than a hundred years ago.There are many reasons for this. Clearly the value of greening our cities is great, and the demand for green walls and roofs is set to continue.

This course is a valuable, unique foundation for anyone working in urban horticulture, including:

  • Landscape Designers
  • Landscape Contractors
  • Nurserymen
  • Horticultural Consultants
  • Gardeners
  • Interior Plantscapers
  • Horticultural Allied traders(anyone supplying equipment or materials for green walls or roofs)
  • Property Developers
  • Town Planners
  • Architects
  • Building Contractors
  • Civil Engineers
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